The present invention relates generally to sheet handling apparatus, and more particularly it relates to a sheet handling apparatus which carries out a stapling process or other processes upon sheets discharged from an image forming apparatus or the like.
Some image forming apparatus of conventional types such as copying machines are provided with a sorter for sorting and storing sheets discharged after an image forming process. Some conventional sorters include a stapler for stapling sorted stacks of sheets.
Japanese Patent Laying-Open Nos. 231757/1989 and 231545/1990 disclose such conventional sorters. These sorters are provided with a plurality of vertically arranged bins for receiving and sorting sheets discharged from a copying machine body. In one type of sorter disclosed therein which has vertically conveyable bins, a stapler is provided at a prescribed position in order to staple stacks of sheets in the bins moved into the stapler. In another type of sorter having bins fixed at predetermined positions, a stapler moves vertically in order to staple the stacks of sheets in the bins.
In the sorters disclosed in these prior art documents, stapled stacks of sheets are received into the bins in a one-to-one correspondence, and it is not possible automatically to sort and staple a number of stacks of sheets greater than the number of bins. Accordingly, in order to process more copies than the number of bins, temporarily an operator must take out all the stapled stacks of sheets from the bins after one sequential process, and restart the same operation. Therefore, considerable time must be expended if a large number of copies is to be processed.
Japanese Patent Laying-Open No. 165270/1988 discloses an example of a sorter capable of sorting and stapling a number of stacks of sheets greater than the number of bins provided in the sorter. This sorter has a storing part for stapling and storing stacks of sheets separately from the sheet-sorting bins. Sorted or stapled stacks of sheets are discharged into the storing part.
In this sorter, however, the sheets of a stack tend to become disarranged while being transported from the sorting part to the storing part, making it difficult to achieve optimally arranged sheets for stapling in the storing part.
The storing part of this sorter is disposed under the bins, and the stapled stacks of sheets must be removed from a low position inconvenient for an operator. In addition, it is not possible to staple a stack of sheets at any given position along its edge.